1. Field of the Invention
The present invention relates to a liquid crystal display.
2. Description of the Related Art
Liquid crystal displays are now the most widely used of the flat panel displays. The liquid crystal displays have two display panels on which electric field generating electrodes such as pixel electrodes and a common electrode are formed, and a liquid crystal layer interposed between the panels. In the liquid crystal displays, a voltage is applied to the electric field generating electrodes so as to generate an electric field in the liquid crystal layer. The alignment of liquid crystal molecules of the liquid crystal layer is determined by the electric field. Accordingly, the polarization of incident light is controlled, thereby providing image display.
The liquid crystal displays also include switching elements connected to the individual pixel electrodes and a plurality of signal lines, such as gate lines and data lines, for controlling the switching elements so as to apply voltages to the pixel electrodes.
In order to prevent a degradation phenomenon that occurs when the electric field is applied in the liquid crystal layer in one direction for a long time, polarities of the data voltage with respect to a common voltage are inverted for every frame, every row, or every pixel.
In these liquid crystal displays, a high-speed driving method is used so as to improve a motion picture display characteristic. However, because high-speed driving requires a larger amount of electric power as the frame speed increases, column inversion is used once per frame to minimize power consumption.
However, the column inversion causes a coupling defect and a stripe defect. Parasitic capacitance arising from an overlap between the data lines and the pixel electrodes causes a data voltage having the same polarity to be continuously applied throughout a frame, thereby generating a coupling defect that causes the upper and lower parts of the display panel of the liquid crystal panel assembly to display images with different luminances. In particular, if a box having a high grayscale level is displayed on a background image having a low grayscale level, a vertical crosstalk phenomenon may occur such that the upper portion and the lower portion of the box have grayscales different from the background image.
The stripe defect refers to a phenomenon in which stripes appear when a data voltage having the same polarity is applied in a vertical direction so that a data voltage having a positive polarity creates an image that is different from a data voltage having a negative polarity.